These units arose from the need to properly manage much smaller groups of airplanes and people than assigned to the existing squadrons in a carrier air group. For example, the first helicopter deployments aboard carriers typically only involved two aircraft and a handful of personnel. As a result, two helicopter utility squadrons were formed, one (HU-1) based on the west coast and one (HU-2) on the east coast, that supplied detachments to aircraft carriers, cruisers, etc. These were big squadrons from the standpoint of aircraft, naval aviators, and maintainers. (They were reportedly even overstaffed, as some naval aviators were reluctant to transition from props to jets and sought an alternative assignment in the burgeoning need for helicopter pilots.)

HU-1 used the tail code UP:

HU-2 was assigned UR:

Similarly, so-called composite squadrons were formed to provide small detachments of specialized mission airplanes (night attack, night fighter, airborne early warning, reconnaissance, etc.) to deploying air groups. These were different in usage from the World War II composite squadrons, which deployed as a unit.

One example is VC-35, which was eventually redesignated VA(AW)-35. As the subsequent designation indicates, it was an all-weather squadron. However, initially it was assigned more missions than simply attack, including ASW, hence the use of C for composite. During the Korean War, it provided detachments to attack carrier air groups deploying from the west coast, flying AD-4Bs, AD-4Ns, and NLs with the squadron tail code NR.

These consisted of VAN (airplane/attack/night) teams of four airplanes, six officers, and 40 enlisted men. There were usually five or six VAN teams deployed at any one time. The squadron itself consisted of more than 100 officers and 650 enlisted men.

Another example is VFP-62, the east coast photo-reconnaissance squadron. It was assigned tail code GA.

Note that by this time, the early 1960s, the tail code on the detachment airplane was changed to that of the air group it deployed with.

In October 1962, VFP-62 had 29 RF-8As (redesignated from F8U-1P the month before) assigned, 20 of which were deployed with seven detachments. Seven of the remainder were flyable when the squadron was tasked with providing photo-reconnaissance of suspected ballistic missile sites in Cuba with an eighth detachment of eight airplanes. The squadron rose to the occasion and received a Presidential Unit Citation, along with a four-RF-8A VMCJ-2 detachment, personally presented by President Kennedy.

Tuesday, December 24, 2013

The F-35C has demonstrated the required 21.4 foot per second sink-rate capability in trials at Patuxent River, accomplishing a major milestone in shore-based carrier-suitability testing.

Lockheed Martin Photo by Dane Wiedmann

2 February 2014 Update:
The "extended evaluation"at Lakehurst mentioned below turns out to have only required a week, concluding on 16 January. All flight test objectives were met according to the Navy. However, the airplane has been returned to Patuxent River for "3-4 months of field-based tests" according to an article in the US Naval Institute News (http://news.usni.org/2014/01/28/navys-f-35c-completes-landing-tests-ahead-october-sea-trials). At-sea trials are scheduled for October 2014, more than a year later than the Lockheed Martin program manager's projection in January 2012. A cynic would say that since this milestone has slipped yet again, this time a year in a little more than a year, the current projection will also come and go without it happening. I hope not. The Navy is already facing a shortfall in deployable fighter airplanes in the latter half of this decade due to the slip in F-35C IOC (Initial Operation Capability) or whatever it's being called these days.

If you read between the lines as I had intended, you would have thought that the fix would not be a big deal. It may not have been, but only now, more than two years later, is the Navy reporting an initial success:

Lockheed Martin Photo

I'm not sure that this was the first arrestment in the recent past, but this one reportedly occurred at Pax River on 19 December 2013. The airplane will now go up to the Naval Air Engineering Station at Lakehurst, New Jersey for an extended evaluation beginning in January.

Thursday, December 19, 2013

For some reason, I had missed getting this small book until this past week, perhaps because the title, Crossing the Line: A BlueJacket's Odyssey in World War II, sounded like a seaman's memoir about crossing the equator, almost certainly on a non-aviation ship.

As it turns out, it is a sailor's memoir but one involving significant wartime events in U.S. Navy carrier aviation. The author, Alvin Kernan, joined the Navy in March 1941 at a teenager looking to leave a small ranch in Wyoming. He selected Ordnance as a specialty and eventually shipped out with Torpedo Six aboard Enterprise, just in time to be aboard for its return to a devastated Pearl Harbor on 8 December 1941. He soon got on flight status as a turret gunner on a Grumman TBF and eventually had to abandon the first aircraft carrier to be named Hornet when it was sunk during the Battle of the Santa Cruz Islands. More heroically, he won a Navy Cross (very unusual for an enlisted man) on the night mission that resulted in the death of Navy Ace Butch O'Hare, in spite of the fact that he might have (but probably didn't) hit O'Hare while firing at a Japanese Betty behind him.

Mustering out after World War II, he used the GI Bill to go to college and a academic career as an Ivy League professor of literature. As a result, he knows how to write about his wartime experience. If you want to read a gritty, well-written, and insightful memoir about Navy carrier aviation from the standpoint of a deckhand and turret gunner, buy this book. Note that there have been at least two editions, with the first published by the Naval Institute in 1994. The one pictured above that I read this week was published in 2007 by Yale and includes a few corrections and new material that came to the attention of the author as a result of comments on the first edition by his former shipmates and knowledgeable readers.

Kernan also wrote The Unknown Battle of Midway, which I did have in my library. It has received mixed reviews for accuracy and ill-informed opinions/statements (see Amazon) but is a pretty good read. (The very best book about the Battle of Midway is probably Shattered Sword: The Untold Story of the Battle of Midway.)

One interesting aspect of the control of the X-47B when it is on deck is that there are two guys, the primary and a backup (in this case Northrop Grumman test pilots), with the remote control hardware; they send commands to the X-47 to stop, to, turn, fold/unfold wings, etc. in accordance with the hand signals from the usual plane director in the yellow shirt just as if they were in the cockpit.

The original post didn't delve much into the Navy's development of inflight refueling of jets. One of the first inflight evaluations involved the North American AJ Savage, with an XAJ-1 being modified to replace the jet engine in the aft fuselage with a refueling reel, hose, and drogue.

North American apparently proposed an AJ-2 in this configuration but it would appear that the extra speed provided by the jet engine was considered to be of more benefit than reducing the available volume in the bomb bay.

Note that the drogue was still a rigid, all-metal cone.

This was soon replaced by the collapsible and presumably lighter shuttlecock-type drogue that was probably more stable in trail than the all-metal cone.

As reported in the original Texaco post, Douglas developed the grandfather of what is now the standard externally mounted refueling store but there were alternatives. McDonnell evaluated a pod for the F3H that the Navy didn't buy. (I had assumed that it was developed by McAir but a caption in the 18 January 1957 issue of Flight identifies it as a Beechcraft Model 102-G refueling store.)

Vought also proposed one for the F7U/A2U program but it probably failed to even reach the hardware stage as a result of the Navy's loss of enthusiasm for the Cutlass. Only North American's design was deployed on the tanker buddy of its FJ-4B alternative to the A4D Skyhawk for nuclear weapon delivery. (Either the North American version was fielded as a backup up to the Douglas D-704 store, consistent with the Navy's belt and suspenders approach to aircraft development at the time, or the low-wing configuration of the FJ-4 precluded the use of the Douglas store.)

Note that the right external store contained the drogue. The matching left-hand store was also equipped with an air-driven pump to transfer its fuel to the right-hand store.

Attempts were made to increase the vertical separation between the tanker and the receiver with booms. The A3D was evaluated with one. It proved unsatisfactory.

External stores with this feature were also developed. This one being considered by the Air Force, here hung on an F-84F, was evaluated by NATC in 1958, only a year or so after the Douglas buddy pod was introduced in the fleet.

Beech also developed a similar pod beginning circa 1960, leasing a civil-register Douglas A-26 as the tanker. It was evaluated by the Navy in 1961, here with an A3J*.

NATC also hung the Beech pod under an F4H, presumably to evaluate it at higher speeds than achievable by the A-26, with the following picture prompting Kim's question.

None of these boom-type solutions proved to be superior overall to the simpler original concept of simply trailing the drogue out the back of a pylon-mounted pod that is still the standard today, almost 60 years after its introduction.

However, the Air Force did introduce a similar arrangement in order to provide drogue-refueling capability from its boom-equipped tankers. As originally implemented on the KC-135, it was referred to, not fondly, as the Iron Maiden. For an illustration and excellent firsthand description of refueling from it, I highly recommend that you read this: http://www.neptunuslex.com/2005/08/13/rhythms-part-xviii/

*The A3J-1 itself served briefly as a tanker, notably on its deployment on Independence.

The refueling store was located in the tunnel which existed to house the nuclear store and jettisonable fuel tanks.

Wednesday, October 16, 2013

Although much maligned, the F7U Cutlass racked up a number of firsts or close seconds for Navy jet fighter airplanes. If Westinghouse had delivered engines with the thrust and fuel consumption that Vought and the Navy were expecting, its reputation might not have suffered so badly. Of course, the Navy would also have had to institute a more formal checkout program (NATOPS) and introduce the angled deck and descending carrier approach sooner. For more, see my monograph on the F7U-1 and my book on the development of U.S. Navy jet fighters.

The F7U-3 was so late to the fleet and disappointing that the Navy made it a one-tour airplane, which meant that few went through a repair and overhaul depot after their initial operational use. Vought also incorporated some light but not very durable structure in the design, such as "metallite", a sandwich of balsa wood between thin sheets of aluminum, and magnesium skins/fittings. Both were prone to deterioration.

So it's somewhat surprising that there are any survivors on display or being refurbished for display. A few, of course, succumbed over time. There are fond memories of gate guards at NAS New Orleans and NAS Jacksonville (the designated repair and overhaul facility for the F7U-3) and playgrounds at the Wheaton Regional Park in Maryland and Holiday Park in Fort Lauderdale (BuNos 129722 and 129582 respectively, the latter last seen at Fort Lauderdale's Executive Airport). However, all these were eventually scrapped.

There are, however, still a handful, a few of which are likely to avoid becoming aluminum cans for many more years.

BuNo 128451: The very first F7U-3, it was rescued from a Navy dump at Socorro, New Mexico for display at the Fred E. Weisbroad Aviation Museum in Pueblo, Colorado. Never restored and in poor condition, the airframe was transferred to the USS Midway Museum in San Diego, California for prospective use in their rebuild of BuNo 129565. However, because it was the prototype, very little of the structure was of use and it has been returned to the Navy for disposition.

BuNo 129554: It ended its Navy career at Geiger Field in Spokane, Washington (now Spokane's International Airport) as a maintenance trainer. It was purchased in May 1958 by Len Berryman and displayed outside the Berryman War Memorial Park in Bridgeport, Washington until mid 1992 when it was sold to Tom Cathcart, who intended to restore it to flying condition. It was in restoration at the Museum of Flight in Everett, Washington for several years and looked to be in very good if incomplete condition when it was offered for sale on eBay in late 2011. As of January 2017 it was still in the restoration area at the Museum of Flight but had been purchased by Al Casby of Project Cutlass in Phoenix, Arizona.

BuNo 129565: It was on display for many years at Olathe, Kansas. It was then transferred to the USS Hornet (CV-12) Museum at the former NAS Alameda in California for restoration. However, before that could be accomplished, it was transferred to the USS Midway (CV-41) Museum in San Diego, California. Some work was accomplished before it was moved to Grand Prairie, Texas in December 2011 for the Vought Heritage Foundation to complete the restoration as they have done for other historic Vought aircraft like the V-173 and F6U. This F7U-3 will eventually be returned back in San Diego for display aboard Midway.

Bill Spidle Photo

BuNo 129622: So far, it has survived the fate of both playground duty and post-playground duty dissection. It ended its Navy career at NAS Glenview, Illinois and was transferred to the Northbrook East Civic Association. After children at Oaklane Elementary School played on it for some years, the forward fuselage became part of Earl Reinart's Victory Air Museum in Mundelein, Illinois while the rest of the airframe (apparently still having the engines installed!) went to J-46 engine dragster builder Fred Sibley in Elkhart, Indiana. The airframe components were subsequently reunited in the collection of noted F7U historian Al Casby in Phoenix, Arizona.

BuNo 129642: It was flown to NAS Willow Grove in May 1957 by VA-12 for static display at an airshow and stricken there to be a maintenance trainer. It is still on display there at the Wings of Freedom Aviation Museum.

BuNo 129655: It was rescued after several years of outdoor display at the Travel Town Museum at Griffith Park, Los Angeles, California and restored to seemingly like-new condition at Paladin Aircraft in San Diego and then transferred to the National Museum of Naval Aviation at NAS Pensacola, Florida. Click HERE for a controllable panoramic view of the cockpit. There are however, a few bogus items like the gun sight and the right hand engine throttle and some missing gauges.

Don Hinton Photo

BuNo 129685: Walter Soplata bought this F7U-3 from NART South Weymouth, Massachusetts for his collection at Newbury, Ohio. Like many of the airplanes on his famous farm, it appears complete although suffering from exposure to the elements.

Sunday, October 6, 2013

One of the problems with basing jet airplanes on aircraft carriers was their lack of endurance. Roughly speaking, compared to a propeller-driven airplane a jet launched carrying more than twice as much fuel and yet had only half the endurance. As a result, carrier operations assumed that when jet airplanes were launched, they were going to be back in less than two hours. If the weather turned bad or the deck became fouled, things got awkward for jet pilots pretty quickly. If there had been any jets aloft in September 1953 during a joint exercise between the U.S. and Royal Canadian Navy's when the carriers involved were beset by fog, they would have all wound up having to ditch. The ability of a propeller-driven airplane to sip fuel eventually resulted in all the airplanes being recovered. For one account, click here.

Inflight refueling was developed primarily to extend the range of bombers but it was soon realized that it could be used to extend the endurance of a jet airplane if required. In September 1955, the Navy announced that all of its fighters in production would be equipped with a probe for refueling in flight. This dictate was extended to all carrier-based jets. Although new designs would have retractable probes, those on existing jets were scabbed-on contraptions that could be retrofitted to ones already delivered. The Douglas F4D Skyrays wound up with a probe mounted on the nose of an external tank.

Douglas developed a "buddy" store that could be carried on a standard pylon for refueling the jets. Its Model D-704 was based on the 400-gallon version of the bomb and tank shape it had developed for low drag. In addition to 300 gallons of fuel, it contained fuel transfer and hydraulic pumps driven by a nose-mounted propeller and a reel that could stream about 40 feet of hose with a drogue on the end. Fuel could be transferred at the rate of 200 gallons per minute.

This is an illustration of the very similar Sargeant-Fletcher refueling pod which replaced the D-704.

The popularity of the AJ Savage, the Navy's first nuclear bomber that could be landed aboard the carrier, increased significantly for Pacific carrier deployments when it was equipped with an inflight refueling capability.

However, the big AJ was still awkward to have on the ship and somewhat of an overkill for the purpose of providing one or two thousand pounds of fuel in extenuating circumstances around the boat. An airplane already in the air group was preferred. At the time, jets were not good candidates for the mission since they couldn't carry much more fuel than they needed for a standard deck cycle.

The tanker of choice in the late 1950s was therefore the AD Skyraider. It was just fast enough to refuel the jets (200 knots indicated was recommended but the AD could go as fast as 300 knots in a descent if necessary) and could carry plenty of jet fuel in addition to its internal bag of aviation gasoline that was enough for a two-hour cycle time.

The disparity of speed performance isn't as apparent in the picture above because the F8U Crusader pilot could raise his wing for low speed flight. However, this F3H Demon pilot is hanging in there with only the slats out.

The AD had to be modified for the mission if more than the 300 gallons in the buddy pod were to be transferred. AD-6 BuNo 139744 and subsequent and all AD-7s were delivered from Douglas with the full tanker capability. Some earlier AD-6s and a few AD-4Bs (the nuclear-capable Skyraiders) were retrofitted with it. Two different configurations would be utilized, "basic" (near ship) and extended range. Both involved the use of 400-gallon drop tanks (the AD normally carried 150 or 300-gallon external tanks) that were modified with a fuel boost-pump kit.

In the basic configuration, jet fuel was carried in both 400-gallon drop tanks and the 300-gallon capacity refueling store, for a total of almost 7,500 lbs of giveaway fuel. The AD pilot would remain at a 145-nm station for 30 minutes using only its 380 gallons of internal fuel. (With the maximum amount of jet fuel on board, the AD was just under its maximum gross weight.)

In the extended range configuration, the left drop tank contained jet fuel and the right, aviation gasoline. The additional gasoline allowed the AD pilot to fly considerably farther out and for longer. However, one or the other configuration had to be selected prior to flight and care taken to insure that the proper fuel was loaded in each tank. While jets could burn just about anything in a pinch (the first jet engines burned aviation gasoline), a piston engine would stop running completely if fed jet fuel, which was basically kerosene.

Thanks to Ed Barthlemes, my go-to guy for Skyraider stuff, for much of the above.

Friday, August 23, 2013

One of the discrepancies that I couldn't resolve before my F7U-1 monograph went to press was the frequently reported first flight date of 29 September 1948 versus a contemporaneous mention of a short flight on 27 September. In my F7U-1 monograph, I wrote "For some reason, (the XF7U-1's first flight on 27 September) only lasted six minutes." In the September 2013 issue of the Smithsonian Air&Space magazine, a letter by a Navy civilian flight test engineer Martin A. Snyder described the flight: "As soon as it lifted off the ground, it started to violently pitch nose up and down. We all were sure that the airplane couldn't fly. However, Baker managed to maintain a semblance of control, came around, and successfully landed. The airplane was towed to the hangar for inspection. We later found out that the longitudinal instability had nothing to do with the aerodynamics. The pitch trim control was a conventional thumb-operated slide switch on top of the control stick, and the switch had been wired backward: When the pilot wanted nose-up trim he got nose-down and vice versa."

I just talked to Martin on the phone and he sounds really sharp, not even allowing for his being 87 years old. I'm sending him a copy of my monograph in hopes that he can provide more information on the early flight test of the Cutlass.

Tuesday, July 30, 2013

Once upon a time, when I was a preteen, I lived with my mother and stepfather in the Philippine Islands. He was assigned as the Assistant Public Works Officer at Naval Air Station Sangley Point, which was on a small peninsula located on the south side of Manila Bay adjacent to the town of Cavite. The runway had been built in early 1945, following the retaking of the area from the Japanese in World War II. It wasn't a very big air station, with almost 50% being the runway, taxiway, and parking areas...

Cdr T.L. Bigley USNR-TAR

In addition to having a runway, Sangley provided a base for Navy seaplanes that patrolled the area.

Cdr T.L. Bigley USNR-TAR

Sangley provided tow-target services to ships and airplanes of the Seventh Fleet operating near Manila Bay.

T.H.Thomason

Another valuable service was providing temporary parking at Sangley's west end for the air group of a carrier when it visited Manila Bay for R&R. This freed up the carrier's deck and hangar for maintenance and cleaning, in addition to providing more room for maintenance on the airplanes themselves, albeit al fresco in most cases.

Cdr G.W. Gregory Jr.

(When we first arrived at Sangley, there were many French Corsairs parked in the west end, having been ferried in from Vietnam following the fall of Dien Bien Phu in early 1954. A French aircraft carrier eventually showed up to take them away.)

Navy aircraft carriers would also offload airplanes at Sangley that were too badly damaged for repair aboard. These would come in by lighter for temporary storage until a ship came by that was headed back to the states.

I spent many happy hours watching the Cougars, Skyraiders, Banshees, etc. taking off and landing since the runway was only a few hundred feet from our house and no one seemed to care if I sat in the grass 50 feet or so off the taxiway. One memorable occasion was when Princeton parked many of its VS-21 S2Fs at Sangley in early 1956 for a week.

I made friends with one of the pilots and got to sit in an S2F with my mother.

You probably haven't heard of NAS Sangley Point. While my stepfather was stationed there, NAS Cubi Point at Subic Bay was established and Sangley became a Naval Station in accordance with a treaty with the Philippines that stipulated there would only be one Naval Air Station, per se. It continued to be an active and important U.S. Navy base until it was turned over to the Philippine government in 1971.

Although I had been enamored with airplanes since I could remember, the two years at NAS Sangley between 1954 and 1956 (and one of the great airplane movies, The Bridges at Toko-Ri) convinced me that I wanted to be a Naval aviator, even if it did mean dying in a ditch in Korea. That, alas, was not to be because of my poor eyesight but I did the best I could under the circumstances.

Sunday, July 28, 2013

One of the many interesting presentations at the Joint Fighter Conference held at NAS Patuxent River, MD in October 1944 concerned the Navy’s upcoming transition from the .50-calibre machine gun to the 20 mm cannon for fighter armament. It was given by Commander J.P. Monroe, head of the armament branch of the Bureau of Aeronautics.

A dive-bomber, the SB2C Helldiver, was the first U.S. Navy carrier based airplane to become operational with cannon, two replacing the four .50-caliber machine guns.

There were teething problems but none were serious relative to the perceived benefits of the larger round and firing mechanism. The Navy was also procuring the F4U-1C with four 20 mm cannon (the “C” suffix probably did not stand for cannon armament per se but was simply the next designation change letter; see http://thanlont.blogspot.com/2013/06/navy-aircraft-designation-suffixes.html).

Commander Monroe noted that, from a gun “horsepower” standpoint, one 20 mm cannon was equivalent to three .50-caliber machine guns. “The 20 will go through .75 inch of armor at 500 yards, while the .50 cal will go through only .43.” He also noted that the cannon barrel was not as susceptible to being damaged with long bursts like the machine gun’s.

There were disadvantages, of course. He noted that the time of flight of the 20 mm shell was longer, .75 second for 500 yards as compared to .62 second for a .50 caliber bullet. The 20 mm installation was also heavier, “one half as much ammunition for the same weight.” The standard of 400 rounds of ammunition for each gun (30 seconds) could therefore not be maintained so only 200 rounds of 20 mm ammunition could be provided per gun. Nevertheless, “The 20 is lethal enough to get far more results out of that 200 rounds than the .50 ever will get out of the 400 rounds.”

Only 200 F4U-1Cs were bought and the F4U-4 retained the six .50-caliber armament configuration, primarily due to ongoing reliability problems with the original Hispano-Suiza cannon. However, the problems were corrected so a handful of F4U-4s were produced with cannon as the F4U-4B (the suffix now designating an armament change, not built for the British) and cannon were standard on the F4U-5.

The Navy’s last propeller-driven fighter, the F8F Bearcat, was initially produced with only four .50-caliber machine guns. However, during production of the -1s, the armament was changed to four 20-mm cannon. The change was externally evident by the longer barrels and the bulges required over the chambers. The cannon were standard on the F8F-2 so no B suffix was required.

The Navy’s first jet, the McDonnell FH-1 Phantom, was produced with four .50-caliber machine guns. The North American FJ-1 Fury was delivered with six. However, the Navy's third jet fighter, the Vought F6U Pirate was armed with four 20 mm cannon, as were all subsequent Navy fighters up through the Vought F8U Crusader.

When the Navy procured the North American F-86 Sabre as a carrier-based fighter, it required the substitution of 20 mm cannon in addition to the changes required for operation to and from aircraft carriers. The armament change was evaluated in the one-off XFJ-2B BuNo 133756, the B suffix again denoting an armament change.

Note that the airplane had nothing in common with the two XFJ-2s other than F-86 parts. It was basically an F-86 with four 20 mm cannon, a Navy gun sight, and a modified windscreen.

The Air Force somewhat belatedly realized the need to transition to 20 mm, a change accelerated by combat experience during the Korean War.

The program was, of course, canceled back in 1991, but like Jarndyce v. Jarndyce in Dickens' Bleak House, it has lingered on as a lawyer's dream.

However, according to an online Aviation Week note dated 21 May 2013:

In a sign of movement in the epic legal battle over the A-12 Avenger II, the Obama administration is asking Congress to allow the Navy to accept a settlement in the case.

In a letter outlining amendments to the administration’s fiscal 2014 request for appropriations, the Pentagon is seeking legislation that would “authorize the Secretary of the Navy to accept and retain in-kind goods and services in lieu of monetary payment, for the purposes of a settlement of the A-12 aircraft litigation.”

More importantly for aviation history, the A-12 mockup has finally been moved to the Veterans Memorial Air Park in Fort Worth, Texas.

These are affordable, well-researched, copiously illustrated monographs. The production quality is excellent. Dana has spent a lot of time on what I call an Easter egg hunt in the National Archives, among other places, and found pictures, drawings, and information previously unpublished and that sometimes contradicts or expands on what we know about a particular airplane type.

Dana is currently sifting through boxes and boxes of 1940s documentation on the F4U-1 Corsair. One of his discoveries is that the F4U-1A designation of what the Navy called the "raised cabin" Corsair was never officially assigned. (There are more revelations but those will have to wait until this next Aircraft Pictorial is published.)

His assertion has generated some debate. After looking at some of my stuff that dates back to 1943 and 1944, I agree with Dana that the Navy did not officially recognize the raised cabin F4U-1 with a designation change.

In the process, I got interested in the Navy's use of letter suffixes to aircraft designations. As a result, I'm pretty sure that the early (through say, 1942) and subsequent meanings have been inadvertently conflated in a confusing way. For example, in explanations in books and on line, you'll find that the letter suffix A stands for many different changes. After examining several examples and in particular relying on an explanation in Introduction to Naval Aviation (NavAer-80R-19) published in January 1946, it appears to me that up through about 1942 there were very few letter suffixes that were related to specific applications or capabilities. (One was P for Photographic.) "A" simply meant the first "minor modification not sufficiently important to change the modification number or where the airplane has been diverted to another service or for a special purpose".

It took a while to find an example of a "B" for a second minor modification that substantiated my thesis, which was the Consolidated NY trainer.

The above is an NY-2 modified with leading edge slats that was being evaluated by NACA in 1928. Consolidated Aircraft* won a 1925 Navy competition for a trainer that was then designated NY-1 (N for trainer, Y for Consolidated, no number between the type letter and the manufacturer letter because it was Consolidated's first trainer for the Navy). According to the interweb, the NY-1A was a modification for gunnery training with a machine gun mounted in the rear cockpit and the NY-1B was an NY-1 modified with the bigger wing and more powerful engine of the NY-2.

So in my opinion the suffix A originally didn't actually stand for amphibious (PBY-1A), armament (J2F-2A), target towing (JRF-1A), floats (TBD-1A), single-stage supercharger (F4F-3A), carrier-basing (SOC-3A), etc. It simply distinguished the modified airplane from the baseline one, like a dash number change signified a more significant change.

At some point early in World War II, however, the use of A appears to have acquired a specific connotation, possibly used only to differentiate a Navy airplane built for the Army, e.g. SB2C-1A. "B" similarly became associated with a Navy airplane that was to be provided to the British, as in F4F-4B. As a result, the first minor modification was now recognized with a "C" suffix and the second, with a "D". This led to the TBF-1C (wing guns and more fuel), the TBF-1D (ASB radar), SB2C-1C (cannon), F4U-1C (cannon), F4U-1D (multiple improvements), etc. Note that "C" did not, in this instance, stand for "cannon": it was a coincidence that the first minor change was to cannons. Thinking that D stood for droppable fuel tank in the case of the F4U-1D was even more fanciful; the F4U-1 had provisions for a droppable fuel tank.

Shortly after this philosophy change, however, mission-specific suffixes began to proliferate and the use of a generic suffix progression in alphabetic order beginning with C was abandoned. One of the early additions was "N" for a "night" fighter (as an indication of the designation system development in progress at the time, the radar-equipped fighter version of the F4U-1 was designated F4U-2; the equivalent F6F-3 modification was the F6F-3N.) But I can't yet say whether a particular suffix used in the mid-1940s was the result of the alphabetical approach or the implementation of specific letters for particular mission capability modifications. "C" was eventually used to designate a land-based airplane that had been adapted to be carrier capable but it's possible that the SNJ-3C was so designated because it was a first minor modification of this trainer. Similarly, "E" came to mean an electronic modification, but the TBF/M-1E might very well have simply been the third minor change of the Avenger.

Consistency in designations was not a Navy hallmark in any event. For example, the modification of the Douglas Devastator to add floats was designated TBD-1A. A similar evaluation of the Vought Vindicator was designated XSB2U-3...

*Consolidated Aircraft was merged with Vultee Aircraft in 1943 to become the Consolidated Vultee Aircraft Corporation. After the war, the company adopted the brand name Convair. It subsequently was acquired by General Dynamics but as a named division. In 1994, GD eventually sold that portion of the division still based in San Diego to McDonnell Douglas Aircraft and the remainder that had been developing and building airplanes in Fort Worth, Texas to Lockheed.

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In 1956, at age 12, I lived on NAS Sangley Point in the Philippine Islands. Always enamored with airplanes, I imprinted on the Cougars, Banshees, and Skyraiders then being deployed. Not able to be a Naval Aviator because I was nearsighted, I instead became an aeronautical engineer and general aviation pilot. Now retired, I write books and monographs on U.S. Navy aircraft.